Field of the Invention
This invention relates to a control apparatus for an autonomously navigating utility vehicle, particularly to an apparatus, used in a utility vehicle that autonomously navigates and works in a working area, that controls operation of a work unit while determining a position (self-position) with respect to the working area.
Description of Related Art
Among prior art control apparatuses that determine a position of the autonomously navigating utility vehicle with respect to a working area in order to control operation of a work unit can be cited, for example, those taught by Patent Documents 1 and 2.
A technical concept taught by Patent Document 1 (International Patent Publication No. WO/2003/104908 corresponding to Japanese Patent No. 4246701, etc.) is to determine a position with respect to a working area by detecting a magnetic field generated by passing an electric current of predetermined pulse width through a boundary wire (electric cable) delineating the working area.
More specifically, generation of current pulses transmitted from a signal generator to the boundary wire and detection by a detector (sensor) are synchronized so as to detect a magnetic field generated by the boundary wire while avoiding influence of noise, thereby determining whether the vehicle has gone outside the working area.
A technical concept taught by Patent Document 2 (European Patent Application Publication No. 2447799) is to encode a current (to be supplied to a boundary wire) by a signal generator and accurately determine a position with respect to a working area by recognizing the code concerned from change in magnetic field intensity detected by a sensor.